A variety of thermal heads have been developed as a printing device of, for example, a facsimile and a video printer. For example, PTL 1 describes a thermal head including a substrate, a plurality of heat generating members arranged on the substrate, a plurality of interconnection lines for supplying electric currents to the heat generating members, and a drive IC for controlling power supplied to the heat generating members. In addition, end portions of the plurality of interconnection lines have a plurality of pads, which are used for being connected to a plurality of terminals of the drive IC, formed therein.
In the thermal head described in PTL 1, since the plurality of heat generating members are densely arranged, the plurality of pads formed in the plurality of interconnection lines connected to the respective heat generating members are also densely arranged on the substrate in limited space. More specifically, the pads are disposed so that the lengths of the interconnection lines connected to the pads gradually increase and, thus, the pads are disposed so as to extend diagonally.